SQL有两种类型,但不多
有一个包含两列的表,SQL有两种类型,但不多,sql,postgresql,having-clause,Sql,Postgresql,Having Clause,有一个包含两列的表,carrier和networktype,我想选择carrier、networktype和行数,这些行正好有两种特定的网络类型,没有其他类型。因此,给出下表 Carrier NetworkType Count 302720 WIFI_11B_G 2 31000 NONE 1 31000 WIFI_11B_G 72 ATT EDGE 4 ATT
carrier
和networktype
,我想选择carrier、networktype和行数,这些行正好有两种特定的网络类型,没有其他类型。因此,给出下表
Carrier NetworkType Count
302720 WIFI_11B_G 2
31000 NONE 1
31000 WIFI_11B_G 72
ATT EDGE 4
ATT HSPA 757
ATT UMTS 98
ATT WIFI_11B_G 163,511
BELL HSPA 3
BELL LTE 16
BELL NONE 57
BELL WIFI_11B_G 5,866
CHINAMOBILE NONE 2
CHINAMOBILE WIFI_11B_G 37
它应该返回:
31000 NONE 1
31000 WIFI_11B_G 72
CHINAMOBILE NONE 2
CHINAMOBILE WIFI_11B_G 37
这是我正在运行的查询
但它只返回正好有2个计数的载体!例如,302720带有WIFI_11B_G,因为它只有2个计数,但没有NONE类型。或者没有无线网络的中国移动
我想我使用having子句是正确的,我想用一个查询,而不是子查询来解决这个问题。谢谢 你似乎在要求两个特定的网络,但你想消灭那些a)没有这两个或b)拥有这两个及以上网络的人。我想
SELECT
mt2.Carrier,
mt2.NetworkType,
mt2.Count
from
( select carrier,
SUM(CASE WHEN network_type IN ( 'NONE', 'WIFI_11B_G')
THEN 1 else 0 end ) as NetworksIWant,
count(*) as AllNetworksForCarrier
from
myTable
group by
carrier ) PreQuery
JOIN myTable mt2
on PreQuery.carrier = mt2.carrier
AND mt2.network_type IN ( 'NONE', 'WIFI_11B_G')
where
PreQuery.NetworksIWant = 2
AND PreQuery.AllNetworksForCarrier = 2
内部的“预查询”获取每个运营商与您感兴趣的运营商匹配的数量,但另外,对于给定的运营商来说,计算所有匹配的数量。然后,通过where查找sum()和count()=2来删除它们。你在说什么?无论怎样,如果你只想返回“无”和“Wifi”,那么你就不应该在
SELECT
mt2.Carrier,
mt2.NetworkType,
mt2.Count
from
( select carrier,
SUM(CASE WHEN network_type IN ( 'NONE', 'WIFI_11B_G')
THEN 1 else 0 end ) as NetworksIWant,
count(*) as AllNetworksForCarrier
from
myTable
group by
carrier ) PreQuery
JOIN myTable mt2
on PreQuery.carrier = mt2.carrier
AND mt2.network_type IN ( 'NONE', 'WIFI_11B_G')
where
PreQuery.NetworksIWant = 2
AND PreQuery.AllNetworksForCarrier = 2